As a technique of obtaining blood flow information inside a patient body, fluoroscopic imaging with the use of contrast agent and an X-ray diagnostic apparatus is known. As an example in fluoroscopic imaging, DSA (Digital Subtraction Angiography) images are acquired by time-sequentially imaging the same region of a patient using an X-ray diagnostic apparatus before and after administration of contrast agent. Specifically, subtraction images corresponding to respective time phases obtained by subtracting a mask image imaged before the administration of contrast agent from an X-ray image of each time phase imaged after the administration of contrast agent are defined as DSA images.
However, blood constantly flows in blood vessels into which contrast agent is injected and inflow of the contrast agent is temporary. Therefore, an operator used to confirm regions of blood vessels and branch points of blood vessels, by imaging dying conditions of the contrast agent in the last several DSA images in his/her mind as afterimages so as to compare them with the dying condition of the latest DSA image.
If more contrast agent is injected into a patient over longer time, regions of blood vessels and branch points of blood vessels can be visualized for a longer time. However, this method undesirably increases burden on a patient.
Thus, novel technology to enable observation of a region of a blood vessel and a branch point of a blood vessel more satisfactorily than conventional technology (regardless of contrast agent amount) has been desired.